<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>查询多个元素</title>
    <style>
        .mycolor{
            color:#fff;
            background-color: #F8DD88;
        }
        .steam{
            text-decoration: initial;
        }
    </style>
</head>
<body>
<ul id="ul">
    <li id="a">油条</li>
    <li id="b" class="steam">包子</li>
    <li id="c" class="steam">米饺</li>
    <li id="d"><a>鱼粉</a></li>
</ul>
<script>
    //返回多个元素节点
    var els=document.querySelectorAll('li.stean');
    els.className='mycolor';
</script>
</body>
</html>